Diversification of methanogens into hyperalkaline serpentinizing environments through adaptations to minimize oxidant limitation.

ABSTRACT: Metagenome assembled genomes (MAGs) and single amplified genomes (SAGs) affiliated with two distinct Methanobacterium lineages were recovered from subsurface fracture waters of the Samail Ophiolite, Sultanate of Oman. Lineage Type I was abundant in waters with circumneutral pH, whereas lineage Type II was abundant in hydrogen rich, hyperalkaline waters. Type I encoded proteins to couple hydrogen oxidation to CO₂ reduction, typical of hydrogenotrophic methanogens. Surprisingly, Type II, which branched from the Type I lineage, lacked homologs of two key oxidative [NiFe]-hydrogenases. These functions were presumably replaced by formate dehydrogenases that oxidize formate to yield reductant and cytoplasmic CO₂ via a pathway that was unique among characterized Methanobacte

SUBMITTER: Fones EM 

PROVIDER: S-EPMC8115248 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature